SBG-TR Metaldetector

[Xtrem]

I want ask Sasho, What is the voltage (P-P), at the point? and why do you prefer this type of oscillator? What is special about it?

[pechkata]

I've wasted a lot of time making detectors as a hobby and I haven't gotten rich from it. It's a good thing I've always been at a high level in industrial electronics.

Don't worry, we're all in this together.
The important thing is to keep the hobby alive.
Stay alive and healthy.

[ivconic]

XX years ago when I first saw that schematic; I immediately made that detector.
I used a cardboard tube and cardboard bodies for the coils.
The detector worked immediately from the first and without any problems.
But after that I lost further interest, life often brings some unpredictable things that disrupt plans.
I have very little memory of the details.
I only remember one detail; audio, it should be improved a bit.
Some slightly more complicated VCO would do a better job there.

[algan]

Hello, Sasho, I would like to ask if the receiver coils have 100 or 150 turns, is the quality of the circuit bad, I can't understand them, and can I use Schottky BAT85 or BAT48 as a replacement for the SFD108 germanium diode. Thank you.

[Mario-j23]

The receiving coil has 100 turns. The diagram is in better quality.

[Mario-j23]

As for the diode, I would look for a 1N60, it is a popular replacement for unavailable germanium diodes.

[algan]

Thank you Mario-j23

[algan]

I started the generator, it works, the amplitude is 42 volts, and the frequency is 7.8 kHz.

[Aziz]

Hi all,

increase the capacitor value of C5 from 270 nF to 1µ and you get more power to the TX coil. The TX coil voltage should rise too.
But I would replace the transistors T1, T2 (BC107) with BC337-40 for more bang.

I like the LC-oscillator.

[algan]

Hi all,

increase the capacitor value of C5 from 270 nF to 1µ and you get more power to the TX coil. The TX coil voltage should rise too.
But I would replace the transistors T1, T2 (BC107) with BC337-40 for more bang.

I like the LC-oscillator.

If you made this circuit board, at what frequency and what results did you achieve in the ground, for example, for a can of Coca-Cola?

[Aziz]

Hi Algan,

If you made this circuit board, at what frequency and what results did you achieve in the ground, for example, for a can of Coca-Cola?

I didn't make the circuit board. I have simulated the transmitter circuit with LTspice only. I haven't seen such an LC oscillator yet and I was interested in the working principle.
The LC oscillator is working fine. It draws less current (power efficient).